Taisha is both the photographer and writer for today’s entry (photos are from last autumn). She writes:
Coreopsis rosea, or the pink tickseed, is a perennial species in the Asteraceae. This taxon is found on sandy shores or marsh edges of coastal eastern North America, in three disjunct groupings: 1) Nova Scotia, Canada; 2) Massachusetts to Delaware, USA; and 3) South Carolina & Georgia, USA. It is also an ornamental species of gardens. Plants bear composite inflorescences, with pink (to white) ray flowers surrounding yellow disc florets. Stems are 10-60 cm in height and lined with a series of oppositely-arranged linear-lanceolate leaves. The dry fruits (cypselae) are oblong without wings or pappi (modified calyces).
The pink tickseed is globally rare. In Canada, it is a federally endangered species (latest assessment: 2013), occurring only at the northern limit of the plant community termed the Atlantic Coastal Plain Flora (ACPF) (a region which extends south to Florida). This floral group is threatened mainly due to habitat loss along the American eastern seaboard and adjacent Canada. In Nova Scotia, dams are of particular concern, as their placement often corresponds with watershed lakes that serve as habitat for species of the ACPF. Over half of the most important shorelines on watershed lakes in Nova Scotia have been lost as ACPF habitat. As Coreopsis rosea is at its northernmost limit in Nova Scotia, it is thought that length of growing season may be a determining factor for its distribution and abundance, as well as other species in the community.
In a study by Lusk & Reekie from the Acadia University Department of Biology, the researchers sought to test the effects of length of growing season (particularly with respect to hydrology and flooded conditions) on species from the ACPF including Coreopsis rosea. The hope was to gain a better understanding of the limiting variables affecting this group to better manage and maintain the plant community.
Beginning at the end of June 2004, Lusk & Reekie transplanted Coreopsis rosea (along with Hydrocotyle umbellata) at three lakes with different hydrological regimes within southwestern Nova Scotia’s Tusket River system. The transplants were planted at several depths on three different occasions using four week intervals. The researchers visited the plants every two weeks, only ceasing over the winter months. Water levels, plant survival, flowering, and plant growth were measured, observed and recorded. At the end of August 2005, the transplants were harvested, dried, and weighed. It was found that transplant date and depth both affected the biomass and flowering of Coreopsis rosea with results varying at each of the lakes. In general, transplants planted higher on the shoreline and earlier in the year were both larger and more copiously flowering than those planted lower along the lakeshores or later in the year.
With this information, Lusk & Reekie suggested that dam reservoirs can provide appropriate habitat for certain Coastal Plain species if water levels are managed. They proposed that lowering water levels of reservoirs in the spring and during times of high precipitation would increase growing season and decrease flood stress. The authors also suggested to raise water levels in the autumn to prevent cold damage. Lastly, the researchers suggested their study can be used to address gaps in the ACPF recovery plan (PDF), in order to better help protect and conserve at-risk species within this group (see: Lusk, J, and EG Reekie. 2007. The effect of growing season length and water level fluctuations on growth and survival of two rare species and at risk Atlantic Coastal Plain flora species, Coreopsis rosea and Hydroctyle umbellata. Canadian Journal of Botany. 85(2):119-131).